Hi Mutale,
I see some confusion in concept about Catalog Code Tabs.
What you referred in the initial post are the Sub-Tabs inside a Catalogs & codes Main tab of a Notification.
What you have referred to in the later post are the Main Tabs of Catalogs. like this
The Difference
The Sub-Tabs of Catalogs will display information corresponding to the line item of the first tab (Object part & Damage Tab). Here you are not free to enter a Cause, Task or Activity without filling an Item line (Object part or Damage)
The Main Tabs are independent Catalog Tabs. You can maintain the line items here independently without any conditions as above.
Lastly:
I hope your initial query has been cleared by looking into the picture, that you can have a separate Causes Tab.
In configuration, you need to have tab 10/Tab16 for this.
Best of Luck
Jogeswara Rao K